


Keep It Simple

by marsteeth



Category: Hunter X Hunter
Genre: Angst, Intercrural Sex, M/M, Non-Consensual Somnophilia, Sibling Incest
Language: English
Status: Completed
Published: 2020-12-01
Updated: 2020-12-01
Packaged: 2021-03-09 22:40:13
Rating: Explicit
Warnings: Rape/Non-Con, Underage
Chapters: 1
Words: 2,988
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27813928
Author URL: https://archiveofourown.org/users/marsteeth/pseuds/marsteeth
Summary: Uncertainty is a feeling Illumi wishes he experienced at that moment but no, he knows exactly what he wants to do.
Relationships: Illumi Zoldyck/Killua Zoldyck
Comments: 9
Kudos: 79





	Keep It Simple

**Author's Note:**

> this is the first thing i've posted in at least four years so hopefully it's a good start!! don't we love some good ol' fashioned Zoldyck quality time.

Illumi knows the rhythm of Killua’s heartbeat as well as he knows his own, knows the way it skips when he runs into Killua in the dark of the hallway, knows how it hammers as electricity pulses through his body, knows best of all the steady drumming of his sleep. 

Thin streaks of moonlight blanch Killua’s sheets and the limbs tangled in them a shade of haunting silver. Soft waves of white fall over his eyes and stick out strangely from the back of his head where he’s slept on them. The hair tucked behind his ears nearly reaches his shoulders now and Illumi notes that he should cut it soon. 

When Illumi slips under Killua’s covers and draws them up gently over them, he hears no change in Killua’s heartbeat. Even as he presses against Killua’s back and lays his arm over that bare, narrow waist, his chest rises and falls without disturbance. Burying his face in Killua’s hair, Illumi breathes in deeply, the soft strands tickling his nose. He smells clean, like soap. Nothing flowery like his mother and Kalluto but nothing intense like his father, he smells like home and he smells familiar. He just smells right.

As he’s pulled into the curve of Illumi’s body, Killua doesn’t wake, just exhales as he shifts languidly. In his moment of adjustment, Illumi takes the opportunity to slip his other arm under Killua’s head. 

Illumi ponders the idea of drifting off, cradled by that smell and the music of Killua’s breath, but he reminds himself to savor it. Getting his throat slit as he sleeps by a startled younger brother is not number one on his priority list and unconsciousness compromises that goal. 

One day he may not mind. 

Killua killing him, that is. 

Illumi isn’t his mother, he doesn’t admire disobedience, he just knows that the only way for Killua to possibly become strong enough to kill him is by Illumi’s hand. No one knows Killua better than he does. No one knows how far Killua can bend before he breaks like he does. 

He imagines Killua’s claws digging into his chest, tearing through his skin into his very soul. 

Killua would look up at him then, not with the joy of having killed his first and greatest enemy, but with the realization that he’s become exactly who Illumi made him. Illumi would see himself in Killua’s eyes, first as a reflection in those wide, wondering pools of blue, then in the way they would glaze over and go cold, just like Aniki. The fleeting shine in Killua’s eyes would fade at the same rate Illumi’s blood would gush from his body, staining Killua’s clothes, his hands, his hair. His blood would stain so darkly and thoroughly into Killua’s skin he would never be able to wash it out. 

The fantasy has Illumi’s dark lashes fluttering closed so he can imagine it better and before he realizes it he finds his free hand wandering over Killua’s body under the sheets. In the pleasant grip of sleep, the skin beneath his roaming palm is warmer than normal, and soft. So, so soft. He caresses the blooming muscles of Killua’s abdomen up to his chest where Illumi pauses for a better feel of that steady heartbeat. Any other time, his dear little brother would jolt awake at the mere creak of his bedroom door, but the days of sleep deprivation training have taken their rightful toll.

Eventually his hand slides down over the protruding bone of Killua’s hip. Despite his growing strength, he always seems to remain delicate beneath Illumi’s fingertips. When he reaches Killua’s thigh he freezes, the slightest echo of a sigh escaping from the weary body pressed against him stopping Illumi in his tracks.

Other than the breath and an almost imperceptible shift to slot himself further into the curve Illumi has made for him, Killua remains undisturbed. 

Illumi catches himself smiling into that mess of wavy hair. He’s all but certain the young assassin will remain asleep until at least midday tomorrow, but the longer he lets his touch drift, the harder it becomes to leave it at that. Not to mention the fact that the longer he feels that warm body sidled up to him, the harder _he_ becomes. Though he had deliberately shifted his hips backwards and away when his hand had found its way around Killua’s waist, Illumi now finds himself canting against the arch of his lower back. 

Uncertainty is a feeling Illumi wishes he experienced at that moment but no, he knows exactly what he wants to do.

As he scoots lower beneath the sheets, Illumi places a kiss onto Killua’s bare, pallid shoulder and tries his best to keep the forearm under Killua’s head as still as possible. When their hips are aligned Illumi stops for a moment, pressing his face against those sharp shoulder blades. He brushes his lips between them as his mouth opens and he breaths warmly and silently against Killua’s skin.

Before a single word can leave Illumi’s mouth he bends his wrist to brush two fingers gently against the center of Killua’s forehead. “Stay asleep,” he whispers with purpose before withdrawing the touch.

With that, he draws his free hand back up Killua’s thigh to the waistband of his briefs where he begins to hook his thumb around but then stops. Instead, Illumi takes his hand back and works on removing his own underwear, attempting to move as little as possible as he shoves them down to his mid-thighs. His length springs eagerly from its restraint and comes to rest on Killua's tailbone. It takes everything in Illumi’s power not to immediately begin sliding it against him, fighting the urge with little more than a soft sigh against his back. Amidst Illumi’s steady breaths come the hints of a shush, hissing quietly as his hands move back to Killua’s body.

Under the sheets and with his brother snuggled up against him, Illumi feels like he’s being boiled alive. His hair falls in messy waves over his torso and down his back but fixing it is a risk he can’t take and he finds himself half-blinded by his own locks as he buries his face into Killua. Eventually he realizes that the heat isn’t entirely his environment’s fault, instead it emanates from inside him, growing ever more unbearable as he tries a roll of his hips against the curve of Killua’s lower back. His lips part in a silent gasp when he does it again, and again, and again. 

Eventually though, it isn’t enough. Even with his long fingers splayed over Killua’s hips and the weight of his sweet brother’s head on his cramping arm, he wants more. 

Illumi’s never thought himself a needy person. Sure, he has preferences in regards to his lifestyle, but very few of them are actual needs. He can sleep underground for weeks, and stay awake for even longer. He can survive without food or water for an impressive amount of time. He can find his way home no matter where he’s dropped. He can wash mud from his clothes and blood from his hair and skin and his nails without complaint. What he can’t do is keep himself from sliding his hand under Killua’s knee and lifting his leg just enough for Illumi to slide his cock in between those pale thighs. 

When Illumi sets Killua’s leg back down he nearly melts into the sensation of soft warmth that envelops him, steeling himself against the shiver that threatens to crawl up his spine. He stays there for a few moments, letting that heavenly feeling saturate his body before he begins to roll his hips at an agonizingly slow pace. 

Before Illumi can get too ahead of himself though he lets his hand slide back up to Killua’s chest, savoring each dip and rise under his fingertips until he gets to the muscle above Killua’s heartbeat where he stops. When he’s certain the drumming is as steady as when he’d first slipped under the sheets he begins to move again, thrusting into the velvety tightness of Killua’s inner thighs steadily. Though something deep in Illumi’s mind craved the idea of becoming one with him in the only way he can think of, he shrugs off the idea. He also wonders if it’s selfish of him not to return the favor, especially since he hasn’t deigned to let his hands slide further down than Killua’s hips, but he decides against that too.

Instead, as Illumi fucks into his darling brother’s thighs, he finds himself matching the unfaltering beating beneath his palm. It takes a few moments for him to realize but when he does, he discovers it to be a thing more satisfying than anything he could’ve imagined. So much so, he lets a low moan slip out against Killua’s back between otherwise silent pants. “Oh, Kil,” Illumi whispers, pressing his lips against Killua’s skin as if it makes better the sinful sighs he’s already heated it with, “You’ll stay asleep for me, won’t you?” The words come out as if they aim to fall on listening ears but Illumi knows that’s not the case, knows as the heat inside him grows insufferable and makes his eyes squeeze shut that this moment is for Illumi alone.

As Illumi’s thrusts waver and he messes up his coordinating rhythm he curses weakly but doesn’t bother to fix it. He’s too caught up in the way Killua’s ass brushes against his stomach and how Killua’s thigh naturally presses down against him in his heavy sleep, keeping Illumi locked in as if he wants it. 

The younger Zoldyck cuddled up to him so automatically, leaned against Illumi’s bare skin with his own so contentedly that maybe, just maybe, something instinctual in him _does_ want it.

Illumi desires it to be true so suddenly it is.

The idea of Killua wanting him in that way, in the desperate, agonizing way Illumi wants him makes him moan softly again. Killua was made for him– made by him, and soon the recognition of that fact will strike Killua so suddenly and so thoroughly, he’ll have no choice but to fall back into the awaiting arms of his devoted eldest brother. Even as Illumi’s movements become erratic, he’s careful not to dig his fingers in too harshly, or even thrust too quickly lest he make any more sound than he already is. Killua will only stay asleep for so long, only stay asleep through so much, and he isn’t willing to compromise this moment for anything. 

As his stomach tightens even more and he bites down on his lower lip to keep the breaths in, he lets his hands roam again, this time letting his palm slide up Killua’s chest to settle around his throat. That pulse beats steadily beneath his fingertips once more, and though he hardly adds any pressure, the sensation of rightful possession washes over him. Illumi would never hurt Killua any more than he can take, would never do anything that wasn’t in his best interest. He would never, but he could. The knowledge that he carefully, painstakingly crafted their dear little heir from nothing, and that still he could break him in the ways only he knows best is enough to finally bring him to the edge. It’s Illumi’s secret for now, but maybe _their_ secret someday. Here and now though, beneath these sheets, under this moonlight, with this body against his own, it is his, all his, only his. 

“Killu–“ Illumi draws in a hitched breath and squeezes his eyes shut even further as he comes between his dear brother’s thighs. As soon as the shocks of euphoria shoot up his body, he drops his grip and balls his hand into a fist, digging his pointed nails into his palm. Open mouth panting between Killua’s shoulder blades, he rolls his hips listlessly until he’s mostly released from the grip of pleasure and he can properly assess the situation.

The ache of shallow crescents in his palm makes its presence known and though Illumi can’t see his own hand, in the sharp silence he can hear the steady dripping of scarlet rivulets onto the sheets. His chest still rises and falls unsteadily but his muscles have begun to relax as he tips his hips back and frees himself from the pressure of Killua’s thigh. When he has retrieved almost all of his appendages, Illumi suddenly realizes that he has another problem to deal with.

Beneath the sheets Illumi has wiped his cum through Killua’s thighs, and spilled it all over the bed just in front of his sweet brother’s own cock. Perhaps that isn’t the worst place he could’ve released it though, he then concludes. A boy Killua’s age would have experienced such a thing all on his own. The discovery of it shouldn’t be any more than an annoyance.

Killua won’t know the difference, but Illumi will.

Smiling through an exhale against Killua’s breath-warmed skin, he’s only comforted for a moment before he recalls the blood. That’s a bigger problem.

Illumi considers cutting Killua.

It would only be a scratch. Killua probably wouldn’t even feel it through his deep slumber and Illumi seriously contemplates the idea before a better one arises. Easing his forearm out from underneath that precious, sleepy head, Illumi sits up slowly. Once he’s propped himself up on his slightly numb arm he can finally see Killua and he pauses for a moment.

Long, ivory lashes lay shut against his pale skin like little angel’s feathers. Pink lips shut as he breathes softly through his nose, only the microscopic twitches of his eyebrows and the occasional sound of his swallowing show Illumi any sign of life. That is, other than his heartbeat, of course. His steady, rhythmic, comforting heartbeat.

When he tears his hungry, reverent eyes from Killua’s moonlight painted face, he’s drawn to his own hand. The crimson in his own pallid palm that spoils the scene. Dipping the pads of his fingers into the tiny pools of blood in his palm, he brings them to Killua’s face, and wipes the blood gently under his nose. Illumi had pierced himself right in front of Killua’s face and as he drags his coated fingers down over Killua’s lips, he smiles again. It’s partly at the way his blood stains that pretty, perfect face, and partly at his own ingenuity. 

The chances of having an accidental emission and nosebleed in the same night are probably not that high, but then again, Killua would never let himself be caught completely unaware in bed so Illumi really would have no idea what his nocturnal bodily habits are. He decides he doesn’t need to worry. That steady slumbering pulse is enough to assure him that there’s no risk of being caught.

In any case, Illumi’s plan is solid and for just a few more moments before he departs he gets to stare at Killua’s mouth partly painted in his blood with the knowledge that it’s his cum between Killua’s thighs. 

As he turns away, Illumi shimmies his underwear back up and shifts his legs over the side to slip from the covers silently, placing each foot down carefully on the old wood. Everything in the house is heavy and creaky and makes it impossible for any normal person to sneak around. Part of the training, Illumi remembers his grandfather saying. 

He’s careful not to leave prints of blood anywhere else as he places the sheets back where he found them, leaning over the bed once more to tuck the blankets all the way up Killua’s torso. Before he straightens back up, Illumi places a quick kiss onto the curve of his cheekbone. “Good boy.” He whispers as he takes a last inhale of that addictive purity before disappearing back into the shadows of the hallway. 

Illumi doesn’t allow himself a single look back as he darts back to his room. He has no desire to be caught scampering through the halls half-naked, and he’s already begun preparing his mildly-concerned reaction for when Killua wakes tomorrow afternoon and complains about a nosebleed, or perhaps a chiding tsk for when he passes Killua’s room and catches him stripping the bed before the butlers can get there. As he shuts his bedroom door behind him, he leans against it and replays the event, only halting the thoughts when his mind starts to take some artistic liberties and he finds himself getting hard again. He can see it all so clearly, even the parts that didn’t actually happen.

* * *

What Illumi doesn’t see as he flops onto his own bed and flashes a self-satisfied smile at his ceiling is when Killua finally dares to open his watery eyes. He raises one hand to his lips and reaches the other down towards the hot wetness between his legs. His blood runs ice cold as he prods around the slick that decorates his friction-heated thighs. There is no question in his mind as to what happened but it isn’t until he draws his fingers up above the covers to examine the slippery whiteness spiderwebbing between them that it hits him. It strikes him deep inside, twisting and burning in his chest, swirling his guts into one endless aching knot.

With his clean hand he traces over his body where the shadow of a touch still lingers, still holds him by the throat and kisses his shoulder, still sighs into his hair and grips his hip, still moans against him as it comes. The sound of Killua’s name spilling from his brother’s lips echoes in his head, growing louder and louder the more he tries to forget it. He claps a hand over his mouth as a pitiful, hitched sound like a whimper escapes him. Mouth agape and breath stuttering, he finally lets it happen. 

Killua lets his heart beat faster. 

**Author's Note:**

> i guess illu taught him too well huh 
> 
> please come be my friend i have lots of nasty thoughts  
>  twitter :) 


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